88 GTU failed emissions
 

Here's my read out from 2 years ago:
15 mph:
RPM - 1817
%CO2 - 14.4
%O2 - 0.45
HC - 58 (118 max)
CO - 0.28 (0.75 max)
NO - 169 (799 max)

25 mph:
RPM - 1973
%CO2 - 14.39
%O2 - 0.48
HC - 62 (93 max)
CO - 0.30 (0.63 max)
NO - 193 (738 max)

Here's todays:
15 mph:
RPM - 1803
%CO2 - 14.2
%O2 - 1.0
HC - 91 (118 max)
CO - 0.49 (0.75 max)
NO - 94 (799 max)

25 mph:
RPM - 2041
%CO2 - 14.3
%O2 - 0.8
HC - 100 (93 max) FAILED
CO - 0.35 (0.63 max)
NO - 70 (738 max)

So the things that changed from 2 years ago....

Then:
Exhaust leak on edge of main cat
Pulling coolant into chambers
Pushing exhaust into coolant

Now:
Gutted pre-cats
Same main cat with leak on crimped edge
Freshly rebuilt motor with no leaks

Do you think it was the gutted pre-cats? I gutted them because the honeycomb melted and clogged them up. The main cat seems to have come uncrimped or something on an edge, so it leaks. Also the pre-cats have a hole in the bottom of each one?? It looks like a manufactured punched hole about 1/4" diameter.

Ideas?

Oh, it's also got a large streetport from the Pineapple template.

Gonna go test the O2 sensor with a multimeter on the green plug. If the O2 sensor is bad, that could be it.

This really sucks.

Well, O2 sensor is alternating what appears to be normally. It's only got about 10k miles on it anyways.

I took the main cat off and welded up the seam that was leaking.

I'm still getting a fffft ffffft sound from the cat at idle after warmed up.

I think it would be safe to guess the cat situation may have an effect on the change. Also the holes around the pipe may have been made by doing back pressure tests to find clogged cats and the plugs fell out

since HC, CO and NOx are all still low, but HC and CO went up, but NOx went down, it might be a little lean.

it still could be the o2 sensor. you may try playing with the AFM, or buy an SAFC or something too.

actually since NOX is so low, maybe advancing the timing would work, NOX WILL go up, but maybe the other two will go down enough, if you had a free retest i'd try that, if not SAFC

How are they allowing you to test with an exhaust leak?
Around here if you have any exhaust leaks they say Bye bye/Fix it.

Safe assumption. It was like a bulb went on in my head when I remembered that after the fact. In the past, I remember reading that the main cat should be sufficient.

I'll see about a free re-test. I'll try advancing the timing a little. I'm trying to avoid dropping another $150+ (SAFC or new cat) on this thing right now; I got bills and crap due.

The dude was cool. He said, "If it passes the sniffer, more power to ya!"



I've been told that I need more miles on the rebuild (it's got about 30 miles on it now) and the HC will come down. Also, how would running 91 octane instead of 87 octane (currently 1/4 tank of 87) affect it? I also realized this morning that my air filter was still on the workbench and not in the car. Geez, how many different ways can I screw up this test?? lmao


Thanks for your input, guys!

so happy that NY killed the roller/sniffer test. so many ways to get around it , just a waste of time

slower burn?

Right. I've read (google) that older cars pass smog easier with premium fuel instead of regular. Is it along the same lines as the ethyl alcohol in the tank, raising the octane?

octane has nothing to do with flame speed....

advancing the timing does get the combustion process started earlier, which SHOULD offer a more complete burn, which SHOULD lower HC and CO. NOX will go up about 200 for every 5 degrees of timing, but you have tons of room there, so it should be fine.

and actually you're so close you might just be able to get it hotter and pass

Do you think I should run premium for the re-test? I'll advance the timing a little bit.

if u are getting a re-test for free I don't see why not.

Turns out my TPS was horribly off (low). I adjusted it back up to ~1k ohm when hot at idle. I also advanced the ignition a tiny bit. It runs/idles sooo much smoother and stronger now!

Gonna have it re-sniffed tomorrow with premium (91) fuel.

good luck! the TPS runs the air control valve, so can make a big difference

Failed again.

CEL does not come on when the key is turned on.

It's not supposed to, it's an 88! Well, when I swapped in the dash from an S5, I musta put the S5 light cluster in as well, that would explain the fuel light coming on when the parking brake is set. Won't pass it despite documentation because the lens-icon-thingy is there "so it's supposed to light up".

The circuitry does not exist for it to light up!

Can't find my S4 light cluster.

FML.

Time for the black Sharpie marker mod!

Huge thanks to ROTARY POWERED for an S4 idiot light cluster!

So....IAT....I hate you.

Found that it was disconnected, but car was running great. Once reconnected it ran like poo. It even died on the smog dyno and had to push the car out. It would NOT idle once warm.

Needless to say, I failed.

Managed to get it home, pulled the plug off the sensor, resistance seemed normal (~5k ohm). Left it unplugged, car improved. This is after fixing the TPS and advancing the CAS a little. I also had 91 in it. My HC's were in the 120's at both 15mph and 25mph.

Gonna go back today or tomorrow without the IAT (as I ran it originally) and with 87 (as I ran it originally) and see how it does then (after the TPS/CAS adjustment). It should pass just fine!

I'm thinking I need to reconnect the IAT at some point and adjust the CAS with a timing light. I just need a timing light. I'll bug someone local this weekend.

if you want the sensor to look plugged in, put some black tape on one of the pins. you could bend the pin out of the way as well, but they are fragile.

So I grabbed an adjustable timing light from Harbor Freight.

I've got:
TPS set at 1k ohm at warm idle (was 400 ohm after first test)
CAS at 10 deg advanced (was 0 deg for first test)
IAT disconnected/hidden (same as first test)
1/4 tank of 87 octane (same as first test)
New air filter (same as first test)

It runs AWESOME! Hoping hoping hoping it passes tomorrow.

FUCK!!!!

5/3/12:
15 mph:
RPM - 1803
%CO2 - 14.2
%O2 - 1.0
HC - 91 (118 max)
CO - 0.49 (0.75 max)
NO - 94 (799 max)

25 mph:
RPM - 2041
%CO2 - 14.3
%O2 - 0.8
HC - 100 (93 max) FAILED
CO - 0.35 (0.63 max)
NO - 70 (738 max)

5/9/12:
15 mph:
RPM - 1835
%CO2 - 14.3
%O2 - 0.6
HC - 149 (118 max) FAILED
CO - 0.27 (0.75 max)
NO - 145 (799 max)

25 mph:
RPM - 2047
%CO2 - 14.5
%O2 - 0.2
HC - 163 (93 max) FAILED
CO - 0.39 (0.63 max)
NO - 86 (738 max)

Today 5/11/12:
15 mph:
RPM - 1827
%CO2 - 14.2
%O2 - 0.7
HC - 61 (118 max)
CO - 0.35 (0.75 max)
NO - 94 (799 max)

25 mph:
RPM - 2049
%CO2 - 14.2
%O2 - 0.7
HC - 140 (93 max) FAILED
CO - 0.27 (0.63 max)
NO - 99 (738 max)

Differences between first (5/3) and last (5/11)...reset TPS from 400ohm to 1kohm and advanced the timing by 10 degrees.

Why did my HC's go UP?!

Do I just need a new damned cat??

Would that little variable resistor have an effect? Everything I can find indicates this is a lean condition, but all my vacuum lines are brand new, injectors are freshly cleaned. The variable resistor is turned all the way left (lean?).

Another $35, and the shop is closed this weekend. I'll find another one.

This is a FRESH rebuild, everything new. It shouldn't be doing this. It passed emissions with 4 coolant leaks before it locked up on me.

Why is your variable resister set to full lean?

Also I feel bad for you guys who need to smog, I just my fc inspected and it has no cats.

I dunno. I never touched it. I'm out of ideas, so I checked it.

Gonna take it to a different smog shop today. That guy yesterday went from 15 to 25 in 2nd, then missed 3rd and almost jumped the car off the rollers.

get a new cat..quit fartin with an old cat.
and try 1/8 of a tank of gas and 1 gallon of methyl hydrate.
get the car NICE and hot( like a 20 minute run) then dump the methyl hydrate into the tank.
do the test..then go and FILL up.(the methyl hydrate is not really friendly so it needs to be diluted.)

Call me captain obvious, but did you try putting the smog pump and ACV back on, or if they're still on there making sure they work? You know, the parts that were designed to make your car pass emissions? I know they are a pain in the ass but you live in CA and that just comes with the territory. Oh and get a new cat.

Yes, they're on, Captain Obvious. :nod:

So this shop today...I set the variable to the middle, seemed logical to me. Took it to this guy. I notice that the first thing he does is run it on the rollers, only idle time is long enough to enter info. The other guy I been taking it to, did all inspections and evap tests first while the car idled.

So it ran through the 15mph and 25mph tests FAST! The guy had a big smile on his face. Then at the very end, he asked where my check engine light was.

Me, "It's the stop lamp in the light cluster"
Him, "No, it's supposed to say check engine"
Me, "No, that's not till like 1990"
Him, "It's 1989."
Me, "This is an 88"
Him, "No its an 89"
Me, "This is my baby, it's an 88 GTU, the first and only year this particular trim was available. It's an 88." (the 88 GTU is different than the 89 GTU, more like the 89 GTUs)
Him, "..."

He looked at the sticker on the door. Apparently it was in the "system" by someone else as an 89 so it was asking for a CEL. He reregistered it as an 88, but had to rerun it on the rollers. All fine and dandy except it had been sitting OFF this whole time, 10 minutes or so while he checked plugs and evap and timing, etc (none of which the other guy did). Apparently I hid the IAT plug well.

Well, it failed again. This time worse, cause apparently 1988 cars are required lower emissions?! WTF?!

Fuck it. Cuttin my losses and buying a new cat. Also gonna do the denatured alcohol. Does anyone make a test pipe that bypasses the first two precats? Or is there a 2-1 header that will bolt in?

At least this guy's givin me free retest.

5/12/12:
15 mph:
RPM - 1802
%CO2 - 14.4
%O2 - 0.5
HC - 200 (85 max) FAILED
CO - 0.31 (0.54 max)
NO - 86 (565 max)

25 mph:
RPM - 2938
%CO2 - 14.6
%O2 - 0.1
HC - 97 (67 max) FAILED
CO - 0.45 (0.34 max)
NO - 61 (522 max)

Good lord why would older cars have stricter emissions? Cali trying to force all old cars off the road?

holy cow, i had something like that happen when i smogged my 79 Rx7. since its a THERMAL reactor, i don't really know how it works, so i had my guy pretest it, and it passed with flying colors.

so he shut it off to enter all the BS in the computer.

he starts it up 10 minutes later and it almost failed! the THERMAL reactor needs heat! but so does a cat! i'd be kind of mad if my smog guy turned the car off before the test.

Well he did it correct the first time, and everything looked great. Then come to find out that someone somewhere entered the wrong year. This guy being super-legit fixed the info, but the computer required him to re-run the car. By the time he re-ran it, it had cooled down.

This is just bullshit.

Limits for 15/25mph:
1989
HC: 118/93
CO: .75/.63
NO: 799/738

1988
HC: 85/67
CO: .54/.45
NO: 565/522

WTF? Why does the older car have stricter limits?? Last I checked, 100ppm was 100ppm whether it came from a 2012 or a 1912 model car. I think they're trying to drive (pardon the pun) consumers to get rid of their old cars and dump money into economy by buying new. However most of that money actually goes to foreign economies because people will want to get something "reliable" if they're having to replace something that obviously isn't.

I hate this state with a passion. If it wasn't for mom's cancer I never would've came back.

i ran into that last year, my friends FC passed smog easily, and then last time it failed with high NOX, and comparing the NOX the car tested the same both times, but the test changed!

the o2 sensor actually was fried, and a new one fixed it, but still

that one does HC in the 20's, co is somewhere around .006 and NOX went from 800 to 231....

car is totally stock, and if i showed you the main cat you wouldn't believe it still works!

I'm sure having the two pre-cats gutted, and a large streetport has a lot to do with it.

With the pre-cats being gutted, it allows the exhaust a place to expand and cool down, not once but twice, so it's not heating the main cat as efficiently as it could.

But still, tightening it down more and more is just bullshit. Maybe I'll see about sleeving the pre-cats so it's straight through without the expansion, keeping the exhaust hotter.

You should put the timing back to stock. It's lowering your exhaust temperatures, and just generally hurts emissions. There's a reason why the stock base timing is -5L -20T.

Below is a chart from an old Mazda study on an early 12A. I know it's not exactly the same, but the basic trend line holds true. Look right across the X axis. That's more timing advance. The line I've put in red is your HC trend line. It goes up when you advance the timing. If you look at those dashed lines at the bottom, it shows that your exhaust temperature goes down when you advance the timing. Lowering the exhaust temperature hurts your catalyst efficiency.

https://www.rx7club.com/attachment.p...1&d=1336956011

Your cat situation is also part of the problem. You've got the two precats gutted and I'm sure your main cat is down on efficiency. Are you sure your port air system is working right or do you just have the airpump putting right into the cat?

That's some good info! Never seen anything like that before.

So by advancing my CAS by 10º, I basically dropped my EGT's ~50ºF which raised my HC's by ~200ppm and raised NOx by ~100ppm.

The theory looks solid. In practice it's not exact, but the trend is there.

I haven't checked the port air system. Since the car passed smog fine before the rebuild, I left all the emissions stuff alone, just cleaned gasket surfaces and obvious carbon buildup and bolted it back on. I assume it's working fine or my numbers would be a lot higher.

New cat on. Is it supposed to sound that sexy for an N/A?!?! Holy shit...

This is the cat I bought and installed.

Off to the smog shop tomorrow.

hmm, that chart actually runs counter to my experience, i had a car last year, that failed NOX, cause they changed the standards, and when i checked the timing, it was at least 10 degrees advanced.

so i put it back to stock, and HC and Co didn't move but NOX does, actually maybe that verifies the chart. it might also be a little different because i'm measuring in the tailpipe after a cat, and @1000HC's they are measuring somewhere else.

what RPM is that chart at?

Yeah, if you moved the timing from 10 degs advanced to 0 and your NOx went down, that verifies the chart.

Here's your problem. It's got a large port job. You've got more overlap. You are showing us readings from a non ported motor vs a ported one. There's no surprise whatsoever that things are different and is completely normal. It's going to have a harder time passing emissions now. It's not to say that it won't but it won't be as easy as stock motor. Emissions standards vary across the country so it may be easier to pass in one state vs another that has them.

Sooo....any suggestions?

I've also shown the numbers of each test with this setup, where the HC's keep climbing.

Going again today after work, with the new (not leaking) catalytic converter and a gallon of denatured alcohol in the tank. It's sitting on about a 1/4 tank right now, it'll be down to 1/8 by the time I get home, go get DNA, then get to the test center.

well yeah, but HC should have dropped too, and they didn't.

if you wanted to check port air, the ACV blows into a series of mufflers (not kidding) and exits on the right front kind of where the undertray meets the wheel well cover, put your finger over the hose, if there is any air coming out at idle, its bad. it should actually not have any air coming out of it until about 2500rpm (it depends on throttle position, so the TPS is important)

TPS has been checked, rechecked and checked again.

I'll look for that hose to make sure. Is it just open to the atmosphere???


-EDIT-
Is it that big nipple pointing straight at the camera, that has the hose (in the next pic) connected to it?
https://www.rx7club.com/picture.php?...ictureid=30697

Is this the hose that should have no air at idle?
https://www.rx7club.com/picture.php?...ictureid=31803

This is why I love Florida

yep! if you're lazy it eventually comes out around the front bumper, so you can check without taking anything apart. if you're not lazy you can take the hose off the acv

Okay, 1 gallon of denatured alky to 3/16 tank and a new cat....passed finally! WOO!!

FILL THE TANK UP with Fresh Fuel...
Now we can all sleep..while JET LEE runs the roads..pickin up the Innocent...turning them to Naughty,...then Darting off like the Enigma he is!!!

Check.


...in progress...

Glad it passed.

Could you post the test numbers?

Thanks.

Of course! I also reset the timing to 0º advance and double checked the TPS.

5/17/12:
15 mph:
RPM - 1767
%CO2 - 14.3
%O2 - 0.5
HC - 36 (85 max)
CO - 0.33 (0.54 max)
NO - 32 (565 max)

25 mph:
RPM - 2875
%CO2 - 14.3
%O2 - 0.5
HC - 34 (67 max)
CO - 0.28 (0.34 max)
NO - 28 (522 max)

congrats! did they do both tests in 3rd gear? my guy does the 15mph in second, and so they both end up around the same RPM